An electro-photographic printer operates by exposing a charged photoconductive drum to selective light patterns to define an electrostatic image on the photoconductive drum. A plurality of toner particles are released from a print cartridge and applied to the photoconductive drum via a developer roller. The toner particles applied to the areas of the photoconductive drum defining the electrostatic image are transferred to a print media, such as paper, cardstock, transparencies, Mylar, cloth, and the like. The print media holding the loose toner particles is passed between a heated fuser roller and a pressure roller to fuse the toner particles to the media, thereby producing a final printed document.
The print cartridge contains a supply of toner in a toner supply chamber. The toner supply chamber is located within the print cartridge such that toner can flow from the toner supply chamber to the developer roller by gravity. Due to the fluid and staining properties of the toner, measures are taken to decrease leakage of excess toner from the print cartridge to unwanted areas. A conventional printer helps control toner dispersal and, thereby, decreases toner leakage by utilizing an assembly of seals within the print cartridge.
A conventional print cartridge, such as the print cartridge generally illustrated at 10 in FIGS. 1 and 2, includes a housing 12, a supply roller 14, a developer end seal 16, a developer end seal 18, a blow-out seal 20, a doctor blade 22, and a developer roller 23 (shown in FIG. 2; not shown in FIG. 1 for clarity). Housing 12 defines a toner supply chamber (not shown) and a dispersion cavity 24. Supply roller 14 extends longitudinally within housing 12, more particularly within the toner supply chamber. Supply roller 14 is flanked on each end by a first support 26 and a second support 28. As such, first and second supports 26 and 28 define an interface area (not shown), which designates the line of contact between supply roller 14 and developer roller 23. With respect to the orientation of FIG. 1 and FIG. 2, a top edge of each support 26 and 28 is covered with developer end seal 16 and developer end seal 18, respectively. Each developer end seal 16 and 18 extends to a front edge 32 of dispersion cavity 24 to interact with blow-out seal 20, which extends along the longitudinal length of front edge 32 of dispersion cavity 24. Doctor blade 22 extends between developer end seal 16 and developer end seal 18 in an orientation substantially parallel to blow-out seal 20. Doctor blade 22 interacts with developer end seal 16 and developer end seal 18 opposite blow-out seal 20. Developer roller 23 extends over and between first and second supports 26 and 28 and, thereby, over developer end seals 16 and 18, partially resting upon developer end seals 16 and 18 and supply roller 14.
During use, print cartridge 10 is oriented such that the toner supply chamber is located above the developer roller 23. Rotation of developer roller 23 induces reciprocal rotation of supply roller 14. The interaction and rotation between developer roller 23 and supply roller 14 causes the toner to be transferred from supply roller 14, located within the toner supply chamber, to developer roller 23. As such, developer end seals 16 and 18 are adapted to decrease leakage of toner at either end of the interface area (not shown). Furthermore, blow-out seal 20 is adapted to decrease leakage of toner out front edge 32 of dispersion cavity 24.
Developer end seals 16 and 18 are generally effective in decreasing toner leakage beyond the ends of interface area (not shown), and blow-out seal 20 is generally effective in decreasing toner leakage out front edge 32 of dispersion cavity 24. However, the interface between each developer end seal 16 or 18 and blow-out seal 20 provides a path for toner to leak or escape from the interface area. Escape of toner from the interface area may allow toner to seep into unwanted areas of the printer and, therefore, may become a detriment to the print quality of the end document. Furthermore, toner leakage may cause a user to get toner on himself or herself or clothing, which may be difficult to clean or remove.